This invention relates in general to a vehicle stability regulating system for land vehicles, and in particular to a vehicle stability regulating system with a yaw rate sensor which delivers a first output signal representative of the yaw rate of the vehicle during operation. Using yaw sensors of this kind, the yaw rate is determined as a measure of the dynamic behavior of the vehicle and used to generate an intervention signal via an electronic control unit.
Known arrangements entail the problem of the output signal of the rotational rate sensor exhibiting a very marked zero position drift due to temperature fluctuations, in particular during the warm-up phase. In order to prevent incorrect regulation procedures caused by the zero position drift, EP 0 893 320 A2 proposes a vehicle regulating device according to which, if the deviation between the yaw rate detected by means of the rotational rate sensor and a yaw rate estimated from the vehicle speed and the steering angle exceeds a threshold value, at least one wheel is braked in order to produce a yawing moment in the vehicle body so as to reduce the yaw rate deviation, with the vehicle regulating device temporarily raising the threshold value until the rotational rate sensor has warmed up.
One disadvantage of the vehicle regulating device which is known from EP 0 893 320 A2 lies in the fact that safety-critical running conditions cannot be entirely excluded, as automatic brake intervention is initiated to reduce the yaw rate deviation. A yaw rate, which is simply estimated, is also used here as initiating criterion for the automatic brake intervention, this inevitably not representing a particularly reliable quantity. Another disadvantage lies in the fact that the efficiency of the vehicle-regulating device is limited to a significant degree, as the threshold value is raised during the warm-up phase, so that the response behavior becomes more sluggish. A further factor is that temperature fluctuations occurring during operation are not taken into account where this known vehicle-regulating device is concerned.
DE 43 40 719 A1 discloses a circuit arrangement for evaluating the signals of a yaw rate sensor in which the temperature-dependence of the signals of the yaw rate sensor is compensated by using an additional temperature sensor. For this purpose the temperature of the yaw rate sensor is detected by the temperature sensor and a correction factor for the signals of the yaw rate sensor is determined and stored for each determined temperature. Since, on the one hand, the temperature sensor may have a temperature-dependent characteristic and, on the other, the connection between a determined temperature of the yaw rate sensor and the temperature-dependent variation of a corresponding signal of the yaw rate sensor may vary, it is impossible to guarantee reliable compensation of temperature-dependent variations of the signals of the yaw rate sensor. Moreover, this circuit arrangement requires an additional sensor, i.e. the temperature sensor.
This invention relates to a device and a method for compensating for the zero position drift of a rotational rate sensor, which has no adverse effects either on safety or efficiency.
The invention contemplates a device for regulating the stability of vehicles for land vehicles that includes an electronic control unit (ECU) for receiving a first, a second and a third output signal (GR, Temp, O-GR). The device also includes a yaw rate sensor (GRS) for delivering the first output signal (GR), which represents a yaw rate of the vehicle, with the second output signal (Temp), which is an output signal of the yaw rate sensor (GRS), representing the operating or ambient temperature of the yaw rate sensor. The device further includes a sensor arrangement (SENS) for delivering the third output signal (0-GR), which represents a non-yawing state of the vehicle. The electronic control unit operates in either a learning mode or an operating mode. In the learning mode, the electronic control unit determines a temperature-related zero offset value from the first output signal in accordance with the second output signal and stores it in a data memory (RAM) if the third output signal indicates a non-yawing state of the vehicle. In the operating mode, the electronic control unit reads a temperature-related zero offset value out of the data memory in accordance with the second output signal and corrects the first output signal with this zero offset value in order to generate a control signal for controlling the road behavior of the vehicle.
The invention also contemplates a method for regulating the stability of vehicles for land vehicles that includes delivering a first output signal. (GR) by means of a yaw rate sensor (GRS) which represents a yaw rate of the vehicle. The method also includes delivering a second output signal (Temp) by means of a yaw rate sensor (GRS) which represents an operating or ambient temperature of the yaw rate sensor. The method further includes delivering a third output signal (0-GR) by means of a sensor arrangement (SENS) which represents a non-yawing state of the vehicle. The first, the second and the third output signals are detected by means of an electronic control unit (ECU). The electronic control unit operates in either a learning mode or an operating mode. In the learning mode, a temperature-related zero offset value is determined from the first output signal in accordance with the second output signal and stored in a data memory (RM) if the third output signal indicates a non-yawing state of the vehicle. In the operating mode a temperature-related zero offset value is read from of the data memory, taking account of the second output signal, and the first output signal corrected with the zero offset value in order to generate a control signal for controlling the road behavior of the vehicle.